1. Field of the Invention
The present invention generally relates to a cleaning device to clean a surface of a rotary member, a process cartridge including the cleaning device, and an image forming apparatus including the process cartridge.
2. Discussion of the Background Art
In general, electrophotographic image forming apparatuses, such as copiers, printers, facsimile machines, multifunction machines including at least two of those functions, etc., form an electrostatic latent image on an image carrier, develop the latent image, transfer the developed image (toner image) onto a sheet of recording media, and then fix the toner image with heat and pressure thereon.
In such image forming apparatuses, typically, the image carrier, a charging device to charge a surface of the image carrier, a developing device to develop the latent image on the surface of the image carrier with developer, a cleaning device to clean the surface of the image carrier after the toner image is transferred therefrom, and the like are housed in a single process cartridge that is detachably attachable to the image forming apparatus to facilitate maintenance of these devices.
Such process cartridge including the cleaning device is described in detail below with reference to FIGS. 10A, 10B, and 11.
FIG. 10A is a schematic cross-sectional view illustrating a cleaning device 20X viewed from an axial direction of an image carrier 100, and FIG. 10B schematically illustrates the cleaning device 20x viewed from a direction indicated by arrow C shown in FIG. 10A perpendicular to the axial direction of the image carrier 100. It is to be noted that a casing 200 that houses the cleaning device 20x, although shown in FIG. 10A, is omitted in FIG. 10B for simplicity.
As shown in FIGS. 10A and 10B, the cleaning device 20x includes the casing 200, in which an opening 200a facing the image carrier 100 is formed; a cleaning blade 300; an entrance seal 400; and a pair of lateral end seals 500. The cleaning blade 300 and the entrance seal 400 are attached to the opening 200a so as to face each other. As shown in FIG. 10B, each end seal 500 is disposed to closely contact an edge portion of the cleaning blade 300 as well as an edge portion of the entrance seal 400.
As shown in FIG. 11, the cleaning blade 300, the entrance seal 400, and the end seals 500 are pressed against a surface of the image carrier 100. As the image carrier 100 rotates in a direction indicated by arrow D shown in FIG. 11, toner, dust, and the like (hereinafter simply “toner T”) adhering to the surface of the image carrier 100 passes the entrance seal 400 and then reaches an edge portion of the cleaning blade 300, where the toner T is removed from the image carrier 100. Then, the toner T is stored in the casing 200.
The function of the seals 400 and 500 is to prevent toner from leaking. More specifically, the entrance seal 400 allows the toner T to pass only in a direction in which the image carrier rotates (hereinafter “image carrier rotation direction”) and does not allow the toner T to pass a direction opposite thereto, thus preventing leakage of the toner T removed from the image carrier 100. In addition, the end seals 500 prevent the toner T from leaking from the edge portions of the cleaning blade 300 and the entrance seal 400.
However, when the end seals 500 are attached to the casing 200, it can happen that a gap S is created between each end seal 500 and the casing 200 as shown in FIG. 12 due to dimensional tolerance and/or assembly tolerance, and the toner T removed from the image carrier 100 can leak through the gap S. If the toner T then enters an image forming unit, image failure might occur. Moreover, if the toner T accumulates inside the image forming apparatus, the toner T might scatter during maintenance work, which is harmful to operators as well as damaging to the image forming apparatus.
Several approaches, described below, have been advanced to eliminate the gap between the end seal and the casing of the cleaning device.
For example, in certain known cleaning devices, filler is used to eliminate the gap between the end seal and the casing.
However, in this case, because applying the filler to the gap and hardening the filler are required, the manufacturing process is rather complicated, and accordingly, assembling the cleaning device requires a longer time. Moreover, because applying the filler to the gap is a delicate operation, the gap might be filled with the filler incompletely, and/or the filler might accidentally adhere to the cleaning blade. If the filler is sandwiched between the image carrier and the cleaning blade, significant image failure can occur.
In other known cleaning devices, a back surface of the end seal is attached to a casing of the cleaning device using double-sided adhesive tape. However, the double-sided adhesive tape is not applied to a given area of the back surface of the end seal, and the portion where the adhesive tape is not present is pressed against an edge surface of the casing so that no gap is created between the end seal and the edge surface of the casing.
In this case, although the end seal can be attached to the casing relatively easily, it is difficult to eliminate the gap between the end seal and the edge surface of the casing completely, and thus this approach does not provide a complete solution to the problem of toner leakage.
In view of the foregoing, a need has arisen to prevent the leakage of the toner from the cleaning device with a simple configuration, which known cleaning devices fail to do.